Ring Closing Methatesis Mediated Synthesis of D-Galactose Derived β-Amino Acids

The first example of a new stereocontrolled synthesis of polyhydroxylated 2-aminocyclopetanecarboxylic acids from hexoses is reported. It consists of the transformation of D-galactose derivative 5 into polysubstituted cyclopentane β-amino acid derivative 12b by means of a sequence that involves a Ring Closing Metathesis of the corresponding polysubstituted 2-methylenehept-6-ene 8b, followed by a stereocontrolled aza-Michael functionalization of the first reported polysubstituted cyclopent-1-ene-1- carboxylic acid ester 10b. Preliminary studies on peptides incorporating these alicyclic - amino acids are also reported. The incorporation of β-amino acid derivative 12b into peptides is also reported.